Climate change could make Sydney deadly by 2060: scientist

Sydney Harbour: Dr Hope warns that the city could be a death trap for vulnerable people.

Graeme Powell, file photo: ABC

The forecast for Sydney in summer 2060 is hot, polluted and deadly to the elderly.

Rising summer temperatures due to global warming, drier weather and smog from transport and bushfires will make the nation's biggest city a health hazard, a scientist has told a major climate change conference.

Martin Cope of the CSIRO says those most at risk will be the increasing number of elderly from heat stress and anyone with asthma or heart complaints.

"We're talking about tripling the number of hospital admissions due to respiratory conditions," he said in Perth, which is hosting the Greenhouse 2009 conference.

"There will be more warmer days, more warmer nights and an older population. It's certainly something we want to plan ahead for," he said, adding the picture might not be so grim if Sydneysiders embraced low-carbon lifestyles and industry.

Dr Cope's team at the CSIRO's Division of Marine and Atmospheric Research used computer models to generate urban weather forecasts for Sydney to test the effects of temperature increases of 1 to 4 degrees Celsius over the current annual maximum.

Higher temperatures caused increased heat stress in the elderly but also helped intensify air pollution, he said.

"From the modelling, we were looking at a 20 per cent increase in the number of days above 30 degrees Celsius ... You can be looking at a 100 per cent increase of the small number of extreme temperature days," he said, referring to temperatures over 40 degrees Celsius.

Dr Cope said the number of people aged 65 and over were expected to double by 2060, increasing the numbers at risk from heat and rising pollution in Sydney.

"That has the biggest effect on the changes in mortality from heat stress. We are talking about roughly a doubling of heat-stress related deaths. If you then factor in a change in the demographic, you could be talking about a doubling again," he said.

Sydney's air would also become more toxic during summer because of higher temperatures and the interaction between sunlight and the chemicals released by burning fossil fuels, even from painting, grass cutting and eucalyptus trees.

"A lot of these emissions are temperature dependent. As things warm up then you get more of the gases being released from the liquids," Dr Cope said.

Add to this the carbon monoxide from tailpipes and ozone created in the smog that blankets the city and "it's a big soup", he said.

By 2060, the projections for Sydney would also be drier with potentially more drought, more dust storms, more high-fire risk weather, he added, further adding materials to the smog mix.

Dr Cope said the computer models also showed how to trim the worst of the impacts, for example, improving household insulation and reducing the city's heat-island effect.

Shifting to electric or hybrid cars would also help.

"That's really the key. The steps that we will take to reduce carbon emissions will also be beneficial to reducing air pollution," he said.